Agricultural harvesters typically include a self-propelled combine with crop threshing, separating, or cleaning equipment, and a header attached to the front of the vehicle that the vehicle carries through the field. The crop standing or lying in the field is collected by the header, which can be a platform, pick-up or corn header, and threshed and separated in the combine in order to remove the grain from the straw and other residues. The straw is either laid down in the field in a swath or chopped and distributed on the field over the working width of the header. The threshed or separated grain is cleaned in a cleaning unit and the chaff residues are also distributed over the field, either by a separate chaff spreader or by the residue distribution arrangement of the straw chopper.
It was proposed to provide two separate straw choppers on a combine (US 2012/0264493 A1), both choppers having a rotor with a rotational axis oriented in the forward direction of the combine. The straw enters the straw choppers from the top and is expelled generally to the side, increasing the achievable distribution width with respect to known straw choppers with a transversely oriented rotor axis. The chaff residues from the cleaning unit are also fed into the straw chopper by a separate fan drawing the chaff through a second inlet at the front of the straw chopper housing. The fan can be mounted inside or outside the straw chopper housing and has its own drive motor.
The separate drive of the fan requires contributes significantly to the cost and weight of the straw chopper arrangement. The air flow necessary to suck the chaff from the cleaning unit into the straw chopper housing creates undesired turbulences in the straw chopper housing contributing to a non-uniform spreading of the crop residues over the field.
It is thus an object of the present invention to provide a residue chopping and distribution arrangement for a combine avoiding or reducing the mentioned disadvantages.